Cathode ray tube recording device



29, 1939- w. HEIMANN CATHODE RAY TUBE RECORDING DEVICE Filed May 4, 1934INVENTOR M44475? /'//M,4A//V ATTORNEY Patented Aug. 2 9, 1939 UNETESTATES PAT T CATHODE RAY TUBE RECORDING DEVICE Walter Heimann, Berlin,Germany, assignor to Allgemeine Elektricitats-Gesellschaft, Berlin,Germany Application May 4, 1934, Serial No. 723,835 In Germany May 9,1933 2 Claims. (Cl. 250-162) This invention relates to a cathode raytube pencil inside the space bounded by the metallic with a low voltagegas-focused pencil for the deposit will not happen. By the provision ofthe oscillographic recording of high frequency oscilmetallic inside coator deposit the negative space lati n charge is drained so that any strayoscillations are In makin oscillographic r ords f high freprecluded.Inasmuch as the metallic coat on the quency oscillations, say, above 10cycles per secglass wall causes additional focusing of the elecnd by theaid of the cathode ray low voltage tube t n p nc the p s u o h gasatmosphere working with gas-focused pencils, the tube exprovided in thetube can be chosen considerably hibits a certain anomalous behavior asregards lower because of the said assistance produced by itssensitiveness, manifesting itself in an initially the insidemetallization of the tube of this invenmarked rise followed by a steepdroop of the sensition compared with what Would normally be retiveness.The reason underlying this phenomeq r f r focusing the electron p n Foxnon is that inside the space between the deflector amp when usin an aron atmosphere, the presplates and the fluorescent screen, owing to theSu ca e reduced from 3 X g u n influence of the proximate glass walls, anegative to 1X 10 h the use O Other gas fi 15 space charge is built upwhich occasions a, supplethe pressures should be chosen in accordanceWith mental oscillation of the electron pencil which behe ni p w of therespective gases in s h comes superposed upon the oscillation of the aWay that the same number of ions will arise pencil caused by th platepotential; as lt inside the space traversed by the electron pencil.

the amplitude experiences an increase and the In this manner, conditionsare SO that undue con- 20 shape of the curve of the oscillations isdistorted. centration or focusing and s the steep op Th inventi n m b stb explained by f of the sensitivity where higher frequencies are ring tth drawing i h concerned, will be substantially diminished so that Fig.1 shows sensitivity curves of a cathode ray by the simultaneous use ofinside metallization tube a a function of th frequency applied andreduced gas pressure extensive uniformizing th r t nd, of thesensitivity graph for the cathode ray tube Fig. 2 shows my invention asapplied to a cathis obtainableode ray tube. One exemplified embodimentof the invention Sensitivity curves are shown in Figure 1, where Shallbe explained y reference to 2 in the the abscissae indicate thefrequency in terms of drawing- R is a cathode y e C mp s 30 Hertz orcycles per second, and the ordinate the an electron accelerator sy t Band the conamplitude of the deflection, in the presence of a Ventionaldeflector plate P s PI and P The constant deflecting potential, say, foran argon electron accelerator System may, for Q gas filling oratmosphere (graph 1) and Xenon consist of an indirectly heated cathode Kwhich filling (graph 2). As can be seen the deflection is of the hollowCavity p an ary an de 35 above 10 Hertz'exhibits a pronounced rise whichAI, a Cylinder W f0 fOCllSSing the developed y, has a very marked crestat 50,000 cycles per secand a main anode anodes Al and A ond, forexample, whereafter the deflection shows are preferably maintained atidentical p ential. a strong droop inside the range between 10 and Thetube is filled, for example. With a g 0 40 10 cycles per second. Thesteep droop in the the Purpose 9 concentrating OC S Hg the 40sensitiveness at around 10 cycles per second may electron Dencll, Say,argon, and It is Op b e be explained by the fact that the sojourn, a itwith anode potentials of a few hundred V. The were, of th ions in tpencil is greater than tube is also supplied with a fluorescent screenF. the length of the period of the pencil moved by NOW, according tothis inVentiOn, the nside th deflector potentiaL The higher t concenwallof the tube in the part located between the 45 n ti or focusing (gaspressure) the more pair of deflector plates P2 and the fluorescent ti blll b th id droop, screen F is provided with a metallic coat or de- Now,according to this invention, these disturbposit, a Silver coat J With aw o e hancing actions are avoidable by providing upon the ing theSensitivity o e t in making Os inside wall of t cathode ray t betweenthe lographic records of high frequency oscillations, 5o

deflecti g plates and the fluor ce t screen a especially those above 10cycles per second. The metallic coat or deposit which is maintained atSaid metallic deposit is Preferably p at a fl e anode potential. Thepotential of the said coat P t l C e Should be taken S0 that the incouldalso be chosen at a lower value, though only side deposit will notextend too close to the deso low that a substantial impediment of thefiector plates in order that mutual influences be- 55 tween the saiddeflector plates and the said metallic deposit may be avoided. It isrecommendable to make the intervening distance at least 3 cm. The saidmetallic deposit may be kept also at a voltage less than that of theanode in that, for instance, a high ohm resistance 0 is inter posed inthe connecting lead between the said metallic deposit and the anode leadas shown in the drawing. In this case the space between the metalliccoat and the deflector plates may be diminished. The potential of themetal coat, however, should not be chosen so low that an appreciableobstruction of the electron pencil during its passage through the spacebounded by the metallic coat is caused.

The gas pressure of the atmosphere filling the tube, according toanother object of this invention is' chosen essentially lower than whatis customarily chosen for such an atmosphere of gas in tubes withoutinside metallization, under otherwise identical conditions. Forinstance, the gas pressure in the presence of an argon filling may be,for instance, 1 10 mm. Hg. column. The sensitiveness curve obtainedforsuch a tube is indicated by graph 3, Fig. 1, applying to an argonatmosphere.

Having thus described the invention, what is claimed is:

1. In cathode ray tube construction, an envelope including thereinelectrode structure for producing upon application of suitablecontrolling voltages a cathode ray beam, fluorescent screen structurefor rendering the produced cathode ray beam visible, beam deflectingmeans for causing the beam to traverse the screen, a metallic coatingupon the inner tube wall extending longitudinally of thetube in the areaintermediate the deflecting means and the screen and removed by alongitudinal spacing of at least three centimeters from the deflectingsystem, said coating being adapted to be maintained at a voltage atleast no greater than the tube anode voltage, and an inert gaseousfilling within the tube at a pressure of the order of 1x 10- mm.mercury.

2. A cathode ray tube construction of the character claimed in claim 1wherein the inert gaseous filling is argon gas.

WALTER HEIMANN.

